Fluid pump

ABSTRACT

Fluid pump ( 10 ) comprises a casing provided with a partition separating a pump chamber and a housing chamber. Impeller ( 43 ) is disposed within the pump chamber. Stator ( 33 ), semiconductor device ( 25 ), terminal ( 37 ), and sheet member ( 29   a ) are disposed within the housing chamber. Terminal ( 37 ) electrically connects the semiconductor device to the stator. Sheet member ( 29   a ) may have rubber elasticity. Preferably, the sheet member has s a first plane surface, which makes contact in a planar manner with the semiconductor device, and a second plane surface which makes contact in a planar manner with the partition of the casing.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2006-313363 filed on Nov. 20, 2006, the contents of which are hereby incorporated by reference into the present application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fluid pump for circulating cooling water that can cool an engine or inverter of a motor vehicle.

2. Description of the Related Art

This type of fluid pump has a casing that comprises a pump chamber and a housing chamber. The pump chamber and the housing chamber are separated by a partition, such that fluid within the pump chamber does not flow into the housing chamber. An impeller is disposed within the pump chamber in a manner capable of rotation. A stator and a control device are disposed within the housing chamber. The control device has a semiconductor device and a terminal. The semiconductor device operates for converting power supplied from the exterior into power for driving the impeller. The terminal electrically connects the semiconductor device with the stator. When the driving power is supplied to the stator, the stator generates driving force for driving the rotation of the impeller. When the impeller has been driven to rotate by the stator, fluid is drawn into the pump chamber and its pressure is increased, then this pressurized fluid is discharged from the pump chamber.

With this fluid pump, power supplied from the exterior is converted into power for driving a motor by the semiconductor device. The semiconductor device generates heat when power supplied from the exterior is converted into power for driving a motor, and consequently this semiconductor device must be cooled. Japanese Laid-open Patent Publication No. 2000-209810 discloses a fluid pump having a metal casing. The semiconductor device is pressed onto and maintained on a wall surface of the metal casing by means of resilient supporting members. The heat generated by the semiconductor device is radiated to the outside air via the metal housing, thus cooling the semiconductor device.

BRIEF SUMMARY OF THE INVENTION

With this type of fluid pump, the external force that the fluid applies to the impeller may vary when the amount of fluid discharged varies during operation. When the external force applied to the impeller varies, the impeller may oscillate about its rotational axis, whereby the casing vibrates. Further, in the case where the fluid pump is attached to the engine room of a motor vehicle, the vibration of the engine is transmitted, whereby the casing vibrates. In the fluid pump disclosed in Japanese Laid-open Patent Publication No. 2000-209810, the semiconductor device is pressed directly onto the metal casing. As a result, there was the problem that the vibration of the casing was also transmitted to the semiconductor device, and this caused a decrease in the durability and reliability of the semiconductor device.

Accordingly, it is an object of the present teachings to provide a fluid pump capable of efficiently cooling the semiconductor device, and capable of reducing the vibration transmitted to the semiconductor device.

In one aspect of the present teachings, a fluid pump may comprise a casing, an impeller, a stator, a semiconductor device, a terminal, and a sheet member. The casing may be provided with a pump chamber, a housing chamber, and a partition that separates the pump chamber and the housing chamber. The impeller may be rotatably disposed within the pump chamber. The stator may be disposed within the housing chamber. The stator generates driving force for driving the rotation of the impeller. The semiconductor device and the terminal may also be disposed within the housing chamber. The terminal electrically connects the semiconductor device to the stator. The sheet member may be disposed within the housing chamber. The first sheet member may have rubber elasticity. The sheet member may include a first plane surface, which makes contact in a planar manner with the semiconductor device, and a second plane surface which makes contact in a planar manner with the partition.

In this fluid pump, the semiconductor device makes contact in a planar manner with the sheet member, and this sheet member makes contact in a planar manner with the partition. As a result, the heat of the semiconductor device is transmitted to the partition via the first sheet member, and is transmitted from the partition to the fluid in the pump chamber. The semiconductor device can thus be cooled efficiently. Further, the sheet member that has rubber elasticity is disposed between the semiconductor device and the partition. As a result, the amount of vibration transmitted from the partition to the semiconductor device is reduced by the sheet member, and the durability and reliability of the semiconductor device can consequently be increased.

In another aspect of the present teachings, a fluid pump may comprise a casing, an impeller, a substrate, a stator, a semiconductor, a terminal, and a sheet member. The casing may be provided with a pump chamber, a housing chamber, and a partition separating the pump chamber and the housing chamber. The impeller may be rotatably disposed within the pump chamber. The substrate, the stator, the terminal, and the sheet member may be disposed within the housing chamber. The stator generates driving force for driving the rotation of the impeller. The semiconductor device may be mounted on an opposite surface of the substrate from the pump chamber side. A first end of the terminal may be fixed to the substrate, and a second end of the terminal may be fixed to the stator. The sheet member may have rubber elasticity. The sheet member may comprise a first plane surface, which makes contact in a planar manner with a surface at the pump chamber side of the substrate, and a second plane surface which makes contact in a planar manner with the partition of the casing. Preferably, the semiconductor device is disposed at a position corresponding to the location where the substrate is making contact with the first plane surface of the sheet member.

In this fluid pump, since the semiconductor device is making thermal contact with the sheet member via the substrate, it is possible to cool the semiconductor device satisfactorily. Further, since the sheet member has rubber elasticity, it is possible to reduce the amount of vibration that is transmitted from the partition to the substrate (and to the semiconductor device).

In another aspect of the present teachings, a fluid pump may comprise a casing, an impeller, a stator, a semiconductor device, and a heat insulating plate. The casing may be provided with a pump chamber, a housing chamber, and a partition separating the pump chamber and the housing chamber. The impeller may be rotatably disposed within the pump chamber. The stator, the semiconductor device, and the heat insulating plate may be disposed within the housing chamber. The stator generates driving force for driving the rotation of the impeller. The semiconductor device is electrically connected to the stator. The heat insulating plate may divide the housing chamber into a stator side and a semiconductor device side. Preferably, the stator is surrounded by the partition and the heat insulating plate.

In this fluid pump, since the stator is surrounded by the partition and the heat insulating plate, heat generated by the stator is prevented from being transmitted to the semiconductor device side. It is thus possible to effectively prevent the semiconductor device from reaching a high temperature.

These aspects and features may be utilized singularly or in combination in order to make an improved fluid pump. In addition, other objects, features and advantages of the present teachings will be readily understood after reading the following detailed description together with the accompanying drawings and claims. Of course, the additional features and aspects disclosed herein may also be utilized singularly or in combination with the above-described aspect and features.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a vertical sectional view of a fluid pump of a first embodiment.

FIG. 2 shows a view from above of a circuit substrate of the first embodiment.

FIG. 3 shows a view from below of the circuit substrate of the first embodiment.

FIG. 4 shows a vertical sectional view of a fluid pump of a second embodiment.

FIG. 5 shows a vertical sectional view of a fluid pump of a third embodiment.

FIG. 6 shows a view from below of a circuit substrate of the third embodiment.

FIG. 7 shows a view from above of the circuit substrate of the third embodiment.

FIG. 8 shows a vertical sectional view of a fluid pump of a fourth embodiment.

FIG. 9 shows a view from below of a circuit substrate of the fourth embodiment.

FIG. 10 shows a view from above of the circuit substrate of the fourth embodiment.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment

A fluid pump 10 of a first embodiment of the present teachings will be described. The fluid pump 10 can be utilized to circulate cooling water for cooling an engine of a motor vehicle, and can be disposed in an engine room of the motor vehicle. As shown in FIG. 1, the fluid pump 10 comprises a lower body 12, and an upper body 50 that is fixed to the lower body 12. The lower body 12 and the upper body 50 are both molded integrally from resin material.

A cylindrical convex part 15 is formed at an upper part of the lower body 12 (at the left side in FIG. 1). A shaft attaching hole 16 a is formed in a center of the convex part 15. A lower end of a shaft 46 is fixed in the shaft attaching hole 16 a. An upper end part of the shaft 46 protrudes upward beyond an upper surface of the convex part 15. An impeller 43 is attached in a manner allowing rotation to the upper end part of the shaft 46. A cylinder-shaped outer wall 17 is formed at an outer circumference of the convex part 15. The convex part 15 and the outer wall 17 are disposed concentrically. A ring-shaped concave part 20 that opens upward is formed by the convex part 15 and the outer wall 17. A cylindrical part 45 of the impeller 43 is housed in the concave part 20.

A connector 21 is formed on the upper part of the lower body 12 (at the right side in FIG. 1). Electric contact 28 is disposed in the connector 21. A lower end of the electric contact 28 is connected with a terminal 26 of a circuit substrate 23. An external power source (not shown) can be connected with an upper end of the connector 21. Power from the external power source can be supplied to the circuit substrate 23 via the electric contact 28 and the terminal 26.

A lower end of the upper body 50 is fixed (by welding for example) to an upper end of the outer wall 17 of the lower body 12. An inlet port 51 and an outlet port (not shown) are formed in the upper body 50. An inner space formed by the lower body 12 and the upper body 50 (i.e., the inner space formed by the outer wall 17, the convex part 15, and the upper body 50) functions as a pump chamber. As a result, the upper body 50 and the lower body 12 correspond to the casing of the claims in the first embodiment.

The impeller 43 is disposed within the pump chamber. The impeller 43 is molded integrally from synthetic resin. The impeller 43 may be manufactured, for example, from material including plastic that contains ferrite powder. The impeller 43 comprises the substantially cylindrically-shaped cylinder part 45, and a blade part 44 that closes one end of the cylinder part 45. The cylinder part 45 is magnetized (polarized) by including magnetic powder therein. A plurality of fins are provided in the blade part 44.

A shaft bearing 47 is disposed in a center of the blade part 44. The impeller 43 and the shaft bearing 47 may be molded integrally by insert molding. The shaft bearing 47 may be formed from polyphenylene sulphide material (PPS material). The shaft 46 is inserted into the shaft bearing 47, and the impeller 43 can rotate freely around the shaft 46. A washer 52 is disposed between the shaft bearing 47 and the convex part 15. A washer 48 is attached to an upper end of the shaft 46 by a screw 49. The washer 48 prevents the impeller 43 from rising upward during rotation. When the impeller 43 is in an attached state with respect to the shaft 46, there is a space formed between an inner surface of the impeller 43 (i.e., an inner circumference surface of the cylinder part 45 and a lower surface of the blade part 44) and the convex part 15 of the lower body 12. Further, a space is also formed between an outer circumference surface of the cylinder part 45 of the impeller 43 and the outer wall 17 of the lower body 12. Furthermore, a space is also formed between a lower surface of the cylinder part 45 of the impeller 43 and the concave part 20 of the lower body 12. Cooling water within the pump chamber passes through these spaces and makes contact with a surface of the convex part 15 of the lower body 12.

A substrate housing part 14 is formed within the lower body 12. A stator housing part 16 is formed within the convex part 15. A bottom of the stator housing part 16 communicates with the substrate housing part 14. The substrate housing part 14 is open toward the bottom. The circuit substrate 23 is inserted into the lower body 12 from the bottom of the substrate housing part 14. When the circuit substrate 23 has been inserted into the lower body 12, a stator 33 is housed in the stator housing part 16, and a substrate 24 is housed in the substrate housing part 14.

In the present embodiment, a heat insulating plate 54 is disposed at the junction between the stator housing part 16 and the substrate housing part 14 (specifically, near a lower end of the stator 33). The stator housing part 16 and the substrate housing part 14 are compartmented by the heat insulating plate 54. The heat insulating plate 54 may utilize, for example, a PA (polyacetal) plate. As a result of providing the heat insulating plate 54, the stator 33 is disposed in a space surrounded by the heat insulating plate 54 and a wall surface of the convex part 15. Potting material 41 is filled into this space (i.e. the stator housing part 16). The stator 33 is submerged in the potting material 41 that has been filled. As a result, heat from the stator 33 is transmitted to the wall surface of the convex part 15 via the potting material 41. The substrate housing part 14 is not filled with potting material, and a lower end thereof is closed by a cover 56. Closing the lower end of the substrate housing part 14 by the cover 56 prevents foreign objects, moisture, etc. from entering the substrate housing part 14.

A material with a high degree of thermal conductivity can be utilized in the potting material 41. By utilizing material with a high degree of thermal conductivity, heat from the stator 33 can be radiated efficiently to the exterior. For example, heat radiating silicon or epoxy resin can be utilized in the potting material 41. Alumina fibers (filler) can be mixed into these resins. The degree of thermal conductivity can be increased further by adding the alumina filler.

The circuit substrate 23 is provided with the substrate 24 and the stator 33 that is fixed to the substrate 24. The stator 33 comprises a stator core 34 and stator coils 35. The stator core 34 is configured from layers of thin steel plate (for example, silicon steel plate) obtained by pressing. A plurality of slots are formed in the stator core 34. A fitting hole 34 a is formed in the center of the stator core 34. A shaft fixing part 16 b of the lower body 12 is fitted into the fitting hole 34 a when the stator 33 is in a housed state in the stator housing part 16. The position of the stator 33 is thus fixed in a predetermined position within the stator housing part 16. When the stator 33 has been fixed in position in the stator housing part 16, an outer circumference surface of the stator 33 faces the inner circumference surface of the cylinder part 45 of the impeller 43.

An upper end of a terminal 37 is fixed to a lower end of the stator core 34. A lower end of the terminal 37 is soldered to a terminal land 37 a (see FIGS. 2 and 3) of the substrate 24. That is, the stator 33 is fixed to the substrate 24 via the terminal 37 and the terminal land 37 a. An upper end part of the terminal 37 passes through the heat insulating plate 54, a central part of the terminal 37 is bent sideways (to the left in FIG. 1), and a lower part thereof is bent downward. As a result, the terminal land 37 a is formed near a left edge of the substrate 24. The stator coils 35 are wound around the slots of the stator core 34. One end of the winding of the stator coils 35 is connected with the terminal 37.

As shown in FIG. 2, the following are mounted in addition to the stator 33 on an upper surface (i.e., the surface at the stator side) of the substrate 24: semiconductor devices, viz. power transistors 25 and power diodes 31, and an electronic part, viz. a choke coil 27. The power transistors 25 are switching elements that switch the power supply to the stator coils 35. The power diodes 31 are devices for absorbing surge voltage at the time when the power supply is switched. The choke coil 27 is a filter for removing noise generated at the time when the power supply is switched. The electronic parts 25, 27, and 31 are heat generating devices that generate heat while operating. Thus, the power transistors 25 and the power diodes 31 correspond to the semiconductor device of the claims.

As shown in FIG. 3, the following electronic parts 32 are mounted on a lower surface of the substrate 24: chip transistors, and chip resistors. As shown clearly in FIGS. 2 and 3, comparatively large electronic parts are mounted on the upper surface of the substrate 24, and comparatively small electronic parts are mounted on the lower surface of the substrate 24.

As shown in FIG. 2, the area surrounded by two dotted lines (i.e., the ring-shaped area surrounded by the two circular dotted lines, hereafter referred to as ring-shaped area) faces the concave part 20 of the lower body 12. The power transistors 25 and power diodes 31 are disposed within this ring-shaped area. Further, the choke coil 27 is disposed adjacent to the ring-shaped area. As shown in FIG. 1, the power transistors 25 and power diodes 31 face a lower surface of the concave part 20, and the choke coil 27 faces an outer surface of the concave part 20.

A ring-shaped sheet member 29 a is disposed above the ring-shaped area of the substrate 24 (see FIG. 1). The sheet member 29 a is molded in a flat shape. The sheet member 29 a has a high degree of thermal conductivity and rubber elasticity. The sheet member can be manufactured from a resilient material (e.g., silicon rubber, silicon rubber containing alumina filler, etc.). A lower surface of the sheet member 29 a makes contact in a planar manner with a portion of upper surfaces of the power transistors 25 and with substantially the entirety of upper surfaces of the power diodes 31. Further, as shown in FIG. 1, the lower surface of the sheet member 29 a makes contact in a planar manner with the central part of the terminal 37. An upper surface of the sheet member 29 a makes contact in a planar manner with the lower surface of the concave part 20 of the lower body 12.

Further, as shown in FIG. 1, a right surface of the choke coil 27 makes contact with an inner wall surface of the lower body 12, and a left surface of the choke coil 27 makes contact in a planar manner with a right surface of a sheet member 29 b. A left surface of the sheet member 29 b makes contact in a planar manner with the outer surface of the concave part 20 of the lower body 12. Like the sheet member 29 a, the sheet member 29 b is formed in a flat shape. The sheet member 29 b also has a high degree of thermal conductivity and rubber elasticity. The sheet member 29 b also can be manufactured from a resilient material (i.e., silicon rubber, silicon rubber containing alumina filler, etc.).

In the fluid pump 10, power is supplied from the circuit substrate 23 to the stator coils 35 of the stator 33. As a result, magnetic force is generated from the stator coils 35, and this magnetic force acts on the cylindrical part 45 of the impeller 43, causing the impeller 43 to rotate. When the impeller 43 rotates, cooling water is drawn into the pump chamber from the inlet port 51. The rotation of the impeller 43 increases the pressure of the cooling water that has been drawn in, and this cooling water is discharged from the outlet port of the upper body 50. At this juncture, the cooling water that has been drawn into the pump chamber also enters the concave part 20 of the lower body 12. The cooling water that has entered the concave part 20 is agitated and frequently redistributed by the rotation of the impeller 43.

When the fluid pump 10 operates, the stator coils 35 of the stator 33 generate heat. Since the stator 33 is surrounded by the wall of the convex part 15 of the lower body 12 and the heat insulating plate 54, the heat of the stator 33 is prevented from being transmitted toward the substrate 24. Further, heat transmitted from the stator 33 to the terminal 37 is transmitted to the concave part 20 via the sheet member 29 a, and is radiated to the cooling water in the pump chamber by the concave part 20. Thus, the heat of the stator 33 is prevented from being transmitted toward the substrate 24, whereby the semiconductor devices 25, 31 is prevented from reaching a high temperature. Further, the potting material 41 is filled into the stator housing part 16. As a result, the heat of the stator 33 is transmitted to the convex part 15 via the potting material 41, and is radiated to the cooling water in the pump chamber by the convex part 15. The heat of the stator 33 is thus radiated efficiently to the cooling water, and the stator 33 is also prevented from reaching a high temperature.

When the fluid pump 10 operates, the power transistors 25, the power diodes 31, and the choke coil 27 mounted on the substrate 24 also generate heat. The heat of the power transistors 25 and the power diodes 31 is transmitted to the concave part 20 via the sheet member 29 a, and is radiated to the cooling water in the pump chamber by the concave part 20. Further, the heat of the choke coil 27 is transmitted to the concave part 20 via the sheet member 29 b, and is radiated to the cooling water in the pump chamber by the concave part 20. The electronic parts mounted on the substrate 24, i.e. the power transistors 25, the power diodes 31, and the choke coil 27, are thus prevented from reaching a high temperature.

In the fluid pump 10, the heat of the stator 33 is prevented from being transmitted toward the substrate 24, and the heat of the power transistors 25 and the power diodes 31 and the choke coil 27 is radiated to the cooling water in the pump chamber via the sheet members 29 a, 29 b and the wall of the concave part 20. The electronic parts 25, 27, 31 are thus effectively prevented from reaching a high temperature.

Further, the power transistors 25, the power diodes 31, and the terminal 37 make contact with the concave part 20 via the sheet member 29 a having rubber elasticity. As a result, there is a decrease in the vibration that is transmitted to the electronic parts 25, 31, 37 via the lower body 12. The electronic parts 25, 31, 37 can consequently be maintained in a suitable manner, and electrical contact (soldered parts) between these electronic parts and the substrate 24 can consequently be maintained satisfactorily.

Further, since the potting material 41 is not filled into the substrate housing part 14, the fluid pump 10 can be made lightweight. Furthermore, since the substrate 24 is fixed to the lower body 12 via the sheet members 29 a, 29 b even though the substrate housing part 14 is not filled with potting material, the substrate 24 can be maintained adequately within the substrate housing part 14.

Second Embodiment

Next, a fluid pump 100 of a second embodiment of the present teachings will be described. The fluid pump 100 can also be utilized to circulate cooling water for cooling an engine. As shown in FIG. 4, the fluid pump 100 is an inner rotor fluid pump. The fluid pump 100 comprises a lower body 112, an upper body 150 that is fixed to an upper end of the lower body 112, and a cover 116 that is fixed to a lower end of the lower body 112.

A concave part 118 is formed in approximately the center of an upper part of the lower body 112, and a convex part 121 is formed at an outer side of the concave part 118. Seen from above, the convex part 121 has a ring shape surrounding the concave part 118. The convex part 121 and the concave part 118 are disposed concentrically. A substrate housing part 114 is formed within the lower body 112. A stator housing part 121 a is formed within the convex part 121. A lower end of the stator housing part 121 a communicates with the substrate housing part 114.

A circuit substrate 123 is housed in the lower body 112. The circuit substrate 123 comprises a substrate 124, power transistors 125 a, 125 b mounted on the substrate 124, and the stator 133 that is connected with the substrate 124 via a terminal (not shown). The power transistor 125 a is mounted on an upper surface of the substrate 124. The power transistor 125 b is mounted on a lower surface of the substrate 124.

When the circuit substrate 123 is in a housed state in the lower body 112, the stator 133 is housed in the stator housing part 121 a. Potting material 141 is filled between an upper surface of the stator 133 and an inner wall surface of the convex part 121. Further, the power transistor 125 a is thermally connected with a wall surface of the concave part 118 via a sheet member 129 a. As shown in FIG. 4, the power transistor 125 b is disposed at a position corresponding to the location where the substrate 124 is making contact in a planar manner with a sheet member 129 b. Thus, the power transistor 125 b is thermally connected with the wall surface of the concave part 118 via the substrate 124 and the sheet member 129 b. The sheet member 129 a, 129 b also have a high degree of thermal conductivity and rubber elasticity. The sheet members 129 a, 129 b can be configured in the same manner as the sheet members 29 a, 29 b of the first embodiment.

A lower end of a shaft 146 is fixed at a center of the concave part 118. An upper end of the shaft 146 is fixed to the upper body 150. An impeller 143 is attached to the shaft 146. The impeller 143 comprises shaft bearings 146 a, 146 b. The impeller 143 is supported by the shaft bearings 146 a, 146 b such that it can rotate around the shaft 146. A cylindrical magnet 145 is provided at the lower end of the impeller 143. When the impeller 143 has been attached to the shaft 146, a lower end part of the impeller 143 is housed in the concave part 118, and the cylindrical magnet 145 faces the stator 133. As a result, when power is supplied from the circuit substrate 123 to the stator 133, magnetic force is generated from the stator 133, and the impeller 143 rotates. When the impeller 143 rotates, cooling water is drawn into a pump chamber 120 (i.e., an inner space surrounded by the lower body 112 and the upper body 150) from an inlet port 151. The rotation of the impeller 143 increases the pressure of the cooling water that has been drawn in, and this cooling water is discharged from an outlet port (not shown). Furthermore, the cooling water that has been drawn into the pump chamber 120 also enters the concave part 118 of the lower body 112. The liquid that has entered the concave part 118 is agitated and frequently redistributed by the rotation of the impeller 143.

In the fluid pump 100, as well, the heat generated by the power transistor 125 a is efficiently transmitted to the wall surface of the concave part 118 of the lower body 112 via the sheet member 129 a, and is radiated from the wall surface of the concave part 118 to the cooling water in the pump chamber 120. Further, the heat generated by the power transistor 125 b is efficiently transmitted to the wall surface of the concave part 118 of the lower body 112 via the substrate 124 and the sheet member 129 b, and is radiated from the wall surface of the concave part 118 to the cooling water in the pump chamber 120. The heat generated by the power transistors 125 a, 125 b is thus radiated efficiently to the cooling water in the pump chamber 120, and the power transistors 125 a, 125 b are prevented from reaching a high temperature. Further, the power transistors 125 a, 125 b make contact with the wall surface of the lower body 112 via the sheet members 129 a, 129 b. As a result, vibration of the lower body 112 is prevented from being transmitted to the power transistors 125 a, 125 b.

Third Embodiment

Next, a fluid pump 200 of a third embodiment of the present teachings will be described. The fluid pump 200 can also be utilized to circulate cooling water for cooling an engine. As shown in FIG. 5, the fluid pump 200 is an outer rotor fluid pump. The fluid pump 200 comprises a lower body 212, an upper body 250 that is fixed to an upper end of the lower body 212, and a cover 216 that is fixed to a lower end of the lower body 212. An impeller 243 is disposed in an inner space (i.e., pump chamber) 220 surrounded by the lower body 212 and the upper body 250. A circuit substrate 223 is housed in the lower body 212. A ring-shaped sheet member 229 makes contact in a planar manner with an upper surface of a substrate 224 of the circuit substrate 223. An upper surface of the sheet member 229 makes contact in a planar manner with a wall of the lower body (specifically, a wall facing a lower end surface of an impeller 243). The sheet member 229 also has a high degree of thermal conductivity and rubber elasticity. The sheet members 229 can be configured in the same manner as the sheet members 29 a, 29 b of the first embodiment.

The circuit substrate 223 comprises the substrate 224 and various electronic devices mounted on the substrate 224. As shown in FIG. 7, a controlling IC 240 and other electronic parts (e.g., chip transistors, chip resistors) are mounted on an upper surface of the substrate 224. As shown in FIG. 6, the following electronic parts are mounted on a lower surface of the substrate 224: a power transistor 236, condensers 232 a, 232 b, 232 c, 232 d, controlling ICs 234 a, 234 b, and a choke coil 238.

The area surrounded by two dotted lines in FIG. 7 is an area that makes contact in a planar manner with the sheet member 229 when the circuit substrate 223 has been housed in the lower body 212. Further, the area surrounded by two dotted lines in FIG. 6 shows an area corresponding to the area (i.e., the area surrounded by two dotted lines in FIG. 7) that makes contact with the sheet member 229. As is clear from FIG. 7, the sheet member 229 makes contact with an upper surface of the controlling IC 240. Further, as is clear from FIG. 6, the power transistor 236, the condensers 232 a, 232 b, 232 c, 232 d, the controlling IC 234 b, and the choke coil 238 is thermally connected with the sheet member 229 via the substrate 224. As a result, heat generated by these electronic parts is radiated in a suitable manner to the cooling water in the pump chamber 220 via the sheet member 229.

In the fluid pump 200, as well, the heat generated by the power transistor 236, the condensers 232 a, 232 b, 232 c, 232 d, the controlling ICs 234 b, 240, and the choke coil 238 is radiated to the cooling water in the pump chamber 220 via the sheet member 229. The heat generated by these electronic parts is thus radiated efficiently to the cooling water in the pump chamber, and these electronic parts are prevented from reaching a high temperature. Further, since these electronic parts make contact with the lower body 212 via the sheet member 229, vibration of the lower body 212 is prevented form being transmitted to these electronic parts.

Fourth Embodiment

Next, a fluid pump 300 of a fourth embodiment of the present teachings will be described. The fluid pump 300 can also be utilized to circulate cooling water for cooling an engine. As shown in FIG. 8, the fluid pump 300 is an inner rotor fluid pump. The fluid pump 300 comprises a lower body 312, an upper body 350 that is fixed to an upper end of the lower body 312, and a cover 316 that is fixed to a lower end of the lower body 312. An impeller 353 is disposed in an inner space (i.e., pump chamber) 320 surrounded by the lower body 312 and the upper body 350. A circuit substrate 323 is housed in the lower body 312. A sheet member 329 makes contact in a planar manner with a center of an upper surface of the circuit substrate 323. An upper surface of the sheet member 329 makes contact in a planar manner with a wall that forms the pump chamber 320. The sheet member 329 also has a high degree of thermal conductivity and rubber elasticity. The sheet members 329 can be configured in the same manner as the sheet members 29 a, 29 b of the first embodiment.

The circuit substrate 323 is provided with a substrate 324 and various electronic parts mounted on the substrate 324. As shown in FIG. 10, comparatively small electronic parts, viz. chip transistors and chip resistors, are mounted on an upper surface of the substrate 324. As shown in FIG. 9, the following electronic parts are mounted on a lower surface of the substrate 324: a power transistor 342, condensers 344 a, 344 b, 344 c, 344 d, controlling ICs 348 a, 348 b, and a choke coil 346. The power transistor 342 is disposed in a center of the lower surface of the substrate 324. Thus, the power transistor 342 is thermally connected with the sheet member 329 via the substrate 324.

In the fluid pump 300, as well, the heat generated by the power transistor 342 is radiated to the cooling water in the pump chamber 320 via the sheet member 329. The heat generated by the power transistor 342 is thus radiated efficiently to the cooling water in the pump chamber 320, and the power transistor 342 is prevented from reaching a high temperature. Further, the power transistor 342 makes contact with the lower body 312 via the sheet member 329. As a result, vibration of the lower body 312 is prevented from being transmitted to the power transistor 342.

Finally, although the preferred representative embodiments have been described in detail, the present embodiments are for illustrative purpose only and are not restrictive. It is to be understood that various changes and modifications may be made without departing from the spirit or scope of the appended claims. In addition, the additional features and aspects disclosed herein also may be utilized singularly or in combination with the above aspects and features.

Furthermore, the technical elements described in this specification and the drawings demonstrate technical merit independently or in various combinations, and are not restricted to the combinations of the claims. Furthermore, the technology presented in the specifications and drawings simultaneously achieves multiple objectives but the technology has merit even if only one of the objectives is achieved. 

1. A fluid pump comprising: a casing provided with a pump chamber, a housing chamber, and a partition separating the pump chamber and the housing chamber; an impeller rotatably disposed within the pump chamber; a stator disposed within the housing chamber, the stator generating driving force for driving the rotation of the impeller; a first semiconductor device disposed within the housing chamber; a terminal disposed within the housing chamber, the terminal electrically connecting the first semiconductor device to the stator; and a first sheet member disposed within the housing chamber, the first sheet member having rubber elasticity, the first sheet member comprising a first plane surface and a second plane surface, the first plane surface making contact in a planar manner with the first semiconductor device, and the second plane surface making contact in a planar manner with the partition of the casing.
 2. The fluid pump as in claim 1, wherein the first semiconductor device is disposed facing the partition of the casing.
 3. The fluid pump as in claim 2, wherein the first sheet member has a third plane surface making contact in a planar manner with the terminal.
 4. The fluid pump as in claim 3, further comprising a substrate disposed within the housing chamber, wherein the first semiconductor device is mounted on the substrate, the terminal has a first end, a second end, and a central part between the first end and the second end, the first end is fixed to the stator, the second end is fixed to the substrate, and the first sheet member makes contact in a planar manner with the central part of the terminal.
 5. The fluid pump as in claim 4, further comprising an electric part mounted on the substrate, and a second sheet member disposed within the housing chamber, wherein the second sheet member has rubber elasticity, the second sheet member comprises a third plane surface and a fourth plane surface, the third plane surface makes contact in a planar manner with the electric part, and the fourth plane surface makes contact in a planar manner with the partition of the casing.
 6. The fluid pump as in claim 5, wherein the first sheet member is formed from silicon resin.
 7. The fluid pump as in claim 1, further comprising a heat insulating plate disposed within the housing chamber, wherein the heat insulating plate divides the housing chamber into a stator side and a first semiconductor device side, and the stator is surrounded by the partition and the heat insulating plate.
 8. The fluid pump as in claim 7, wherein the heat insulating plate is disposed near an end side of the stator.
 9. The fluid pump as in claim 8, wherein potting material is filled into only a space at the stator side of the housing chamber.
 10. The fluid pump as in claim 1, further comprising a substrate, a second sheet member, and a second semiconductor device, wherein the substrate is disposed within the housing chamber, the second sheet member is disposed within the housing chamber, the second sheet member having rubber elasticity, the second sheet member comprising a fourth plane surface and a fifth plane surface, the fourth plane surface making contact in a planar manner with a surface at the pump chamber side of the substrate, and the fifth plane surface making contact in a planar manner with the partition of the casing, and the second semiconductor device is mounted on an opposite surface of the substrate from the pump chamber side, at a position corresponding to the location where the substrate is making contact with the fourth plane surface of the second sheet member.
 11. The fluid pump as in claim 10, wherein the first semiconductor device is mounted on a pump chamber side surface of the substrate, and first end of the terminal is fixed to the substrate, the second end of the terminal is fixed to the stator.
 12. A fluid pump comprising: a casing provided with a pump chamber, a housing chamber, and a partition separating the pump chamber and the housing chamber; an impeller rotatably disposed within the pump chamber; a substrate disposed within the housing chamber, a stator disposed within the housing chamber, the stator generating driving force for driving the rotation of the impeller; a semiconductor device mounted on an opposite surface of the substrate from the pump chamber side; a terminal disposed within the housing chamber, wherein a first end of the terminal is fixed to the substrate, and a second end of the terminal is fixed to the stator; and a sheet member disposed within the housing chamber, the sheet member having rubber elasticity, the sheet member comprising a first plane surface and a second plane surface, the first plane surface making contact in a planar manner with a surface at the pump chamber side of the substrate, and the second plane surface making contact in a planar manner with the partition of the casing, wherein the semiconductor device is disposed at a position corresponding to the location where the substrate is making contact with the first plane surface of the sheet member.
 13. The fluid pump as in claim 12, wherein the sheet member has a third plane surface making contact in a planar manner with the terminal.
 14. The fluid pump as in claim 13, wherein the terminal has a central part between the first end and the second end, and the sheet member makes contact in a planar manner with the central part of the terminal.
 15. The fluid pump as in claim 14, wherein the sheet members is formed from silicon resin.
 16. A fluid pump comprising: a casing provided with a pump chamber, a housing chamber, and a partition separating the pump chamber and the housing chamber; an impeller rotatably disposed within the pump chamber; a stator disposed within the housing chamber, the stator generating driving force for driving the rotation of the impeller; a semiconductor device disposed within the housing chamber, the semiconductor device being electrically connected to the stator; and a heat insulating plate disposed within the housing chamber, wherein the heat insulating plate divides the housing chamber into a stator side and a semiconductor device side, and the stator is surrounded by the partition and the heat insulating plate.
 17. The fluid pump as in claim 16, wherein the heat insulating plate is disposed near an end side of the stator.
 18. The fluid pump as in claim 17, wherein potting material is filled into only a space at the stator side of the housing chamber.
 19. The fluid pump as in claim 18, further comprising a sheet member disposed within the housing chamber, the sheet member having rubber elasticity, the sheet member comprising a first plane surface and a second plane surface, the first plane surface making contact in a planar manner with the semiconductor device, and the second plane surface making contact in a planar manner with the partition of the casing.
 20. The fluid pump as in claim 19, wherein the sheet member is formed from silicon resin. 